Towards Composable Concurrency Abstractions

Swalens, Janwillem; Marr, Stefan; Koster, Joeri De; Cutsem, Tom Van

doi:10.4204/eptcs.155.8

Cited by 3 publications

(6 citation statements)

References 6 publications

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“…This bug and its incorrect way of using the mixture of actors and futures is a good example of the misuse of the mixture of concurrency models [Swalens et al 2014]. These mixtures are often necessary for the implementation of real-world actor software [Swalens et al 2014;], however their misuse can cause bugs. The race in Figure 9 is a simple bug with a well-known anti-pattern of closing over the mutable sender() in the callback of a future.…”

Section: Root Cause 2: Racementioning

confidence: 99%

Actor concurrency bugs: a comprehensive study on symptoms, root causes, API usages, and differences

Bagherzadeh

Fireman

Shawesh

et al. 2020

Proc. ACM Program. Lang.

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Actor concurrency is becoming increasingly important in the development of real-world software systems. Although actor concurrency may be less susceptible to some multithreaded concurrency bugs, such as lowlevel data races and deadlocks, it comes with its own bugs that may be different. However, the fundamental characteristics of actor concurrency bugs, including their symptoms, root causes, API usages, examples, and differences when they come from different sources are still largely unknown. Actor software development can significantly benefit from a comprehensive qualitative and quantitative understanding of these characteristics, which is the focus of this work, to foster better API documentation, development practices, testing, debugging, repairing, and verification frameworks. To conduct this study, we take the following major steps. First, we construct a set of 186 real-world Akka actor bugs from Stack Overflow and GitHub via manual analysis of 3,924 Stack Overflow questions, answers, and comments and 3,315 GitHub commits, messages, original and modified code snippets, issues, and pull requests. Second, we manually study these actor bugs and their fixes to understand and classify their symptoms, root causes, and API usages. Third, we study the differences between the commonalities and distributions of symptoms, root causes, and API usages of our Stack Overflow and GitHub actor bugs. Fourth, we discuss real-world examples of our actor bugs with these symptoms and root causes. Finally, we investigate the relation of our findings with those of previous work and discuss their implications. A few findings of our study are: ❶ symptoms of our actor bugs can be classified into five categories, with Error as the most common symptom and Incorrect Exceptions as the least common, ❷ root causes of our actor bugs can be classified into ten categories, with Logic as the most common root cause and Untyped Communication as the least common, ❸ a small number of Akka API packages are responsible for most of API usages by our actor bugs, and ❹ our Stack Overflow and GitHub actor bugs can differ significantly in commonalities and distributions of their symptoms, root causes, and API usages. While some of our findings agree with those of previous work, others sharply contrast. CCS Concepts: • Theory of computation → Concurrency; • General and reference → Empirical studies.

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Section: Root Cause 2: Racementioning

confidence: 99%

Actor concurrency bugs: a comprehensive study on symptoms, root causes, API usages, and differences

Bagherzadeh

Fireman

Shawesh

et al. 2020

Proc. ACM Program. Lang.

View full text Add to dashboard Cite

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“…We observe that when the language constructs of different concurrency models are combined, their original guarantees are often invalidated. In a case study of Clojure [58], we found several such cases. For instance, when a message is sent to a channel in a transaction, and the transaction rolls back, the message is not retracted.…”

Section: Actorsmentioning

confidence: 88%

“…In almost all of these examples, the languages impose no restrictions on combinations of concurrency models and developers can freely mix multiple models in a single program. (Swalens et al [58] perform a case study of Clojure.) However, as we will see in the next section, these naive combinations can break the guarantees of the separate models, potentially introducing bugs even in code considered 'safe'.…”

Section: Motivations For Combining Concurrency Modelsmentioning

confidence: 99%

Chocola

Swalens

Koster

Meuter

2020

ACM Trans. Program. Lang. Syst.

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Programmers often combine different concurrency models in a single program, in each part of the program using the model that fits best. Many programming languages, such as Clojure, Scala, and Java, cater to this need by supporting different concurrency models. However, existing programming languages often combine concurrency models in an ad hoc way, and the semantics of the combinations are not always well defined. This article studies the combination of three concurrency models: futures, transactions, and actors. We show that a naive combination of these models invalidates the guarantees they normally provide, thereby breaking the assumptions of programmers. Hence, we present Chocola : a unified language of futures, transactions, and actors that maintains the guarantees of all three models wherever possible, even when they are combined. We describe and formalize the semantics of this language and prove the guarantees it provides. We also provide an implementation as an extension of Clojure and demonstrated that it can improve the performance of three benchmark applications for relatively little effort from the developer.

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“…Tasharofi et al [16] have shown that developers effectively combine multiple models in a single program: in a sample of 15 GitHub projects in Scala that use the actor model, 12 combined it with another model (illustrated in Figure 1). 8 out of 15 programs used actors and futures and 10 out of AGERE'18, November 4-9, 2018, Boston, MA, USA 2018.…”

Section: Introductionmentioning

confidence: 99%

“…8 out of 15 programs used actors and futures and 10 out of AGERE'18, November 4-9, 2018, Boston, MA, USA 2018. 15 programs actors and threads, including 6 which used all three models. Only 3 out of the 15 programs used only actors.…”

Section: Introductionmentioning

confidence: 99%

Chocola: integrating futures, actors, and transactions

Swalens

Koster

Meuter

2018

Proceedings of the 8th ACM SIGPLAN International Workshop on Programming Based on Actors, Agents, and Decentralized Control

Self Cite

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Developers often combine different concurrency models in a single program, in each part of the program using the model that fits best. Many programming languages, such as Clojure, Scala, and Haskell, cater to this need by supporting different concurrency models. However, they are often combined in an ad hoc way and the semantics of the combination is not always well defined.This paper studies the combination of three concurrency models: futures, actors, and transactions. We show that a naive combination of these models invalidates the guarantees they normally provide, thereby breaking the assumptions of developers. Hence, we present Chocola: a unified framework of futures, actors, and transactions that maintains the guarantees of all models wherever possible, even when they are combined. We present the semantics of this model and its implementation in Clojure, and have evaluated its performance and expressivity using three benchmark applications.

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Towards Composable Concurrency Abstractions

Cited by 3 publications

References 6 publications

Actor concurrency bugs: a comprehensive study on symptoms, root causes, API usages, and differences

Actor concurrency bugs: a comprehensive study on symptoms, root causes, API usages, and differences

Chocola

Chocola: integrating futures, actors, and transactions

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